Exercise is a known stressor that has influence over many different physiological systems in the body. There is evidence in the literature that long-term training in athletes can negatively affect antimicrobial protein levels in the oral cavity. Furthermore it has been reported that athletes face a higher incidence of upper respiratory tract infection (URTI) compared to more sedentary individuals. Based upon the reports in the literature, it is understood that long-term training for sport performance is a stressor that can both elevate physiological potential for in the athletic arena, but may depress function in other system. Moreira et al. reported that a 2-week detraining period after a competitive soccer season attenuated Immunoglobulin A (sIgA) suppression and symptomology of URTI due to training. From this study it can be suggested that mucosal immunity can quickly rebound if rest and recovery are allowed for athletic populations. However, the demands placed upon athletes, reduced mucosal immunity and risk for URTI are likely to remain an issue into the future.
It has also been determined by previous research that certain forms of acute athletic performance and exercise have the ability to suppress immunoglobulin secretion in the oral cavity. However, most of these exercises are long duration and aerobic, the evidence for the changes in antimicrobial protein with short-term intermittent exercise is less clear with some evidence suggesting no change in immunoglobulin type A. Additionally, Li and Gleeson reported that 60% maximum aerobic capacity (V02 max) cycling for 2 hours did not negatively impact sIgA secretion rates. However, MacKinnon and Jenkins had previously reported a decline in sIgA with intense interval exercise (0.075 g*kg−1) on a cycle ergometer. Though there is much study yet needed to fully elucidate the responses of antimicrobial proteins in the saliva with all forms of exercise there is enough evidence that further study is warranted particularly regarding methods to increase antimicrobial protein levels.
Some botanicals, such as baker's yeast beta glucan, have been shown to increase sIgA in saliva and help decrease symptoms of cold and flu post exercise. Shiitake mushrooms are another natural food substance that is known to contain beta glucans, which may be beneficial for human health. Shiitake mushrooms have been demonstrated to have anti-oxidant activity post exercise, but no evidence currently exists to examine changes in oral anti-microbial protein levels post exercise. Therefore, the purpose of the initial investigation was to examine the effects of a botanical supplement on secretory immunoglobulin A and alpha defensing levels post-exercise.